I also did that with git, but it's no comparison in ergonomics. For instance, "move this hunk two commits up" is a task that makes many git users sweat. With jj it's barely something that registers as a task.
> For instance, "move this hunk two commits up" is a task that makes many git users sweat.
Citation needed. You split the commit anyway you like, e.g. with the mouse or using cursor movements or by duplicating and deleting lines. Then you move it with the mouse or cursor or whatever and squash it into the other commit. Maybe some people never intend to do it, but then these probably also don't want to learn JJ. I guess this is more of a selection bias, that these that care about history editing are also more likely to learn another VCS on their own.
You sweat because you are working with the CLI. Git is intrinsically "graphical". Use a good GUI client or higher level interface (maybe jj) to manipulate git graphs --- stop worrying about "how" (i.e. wrangling with CLI to achieve what you want) and focus more on "what".